What important factor is present in the creation of these pottery pieces?

Pottery pieces:

Pottery is the clay is modelled, dried, fried. Clay is the natural material dug from earth., which is decomposed from the rock within the earth crust from the million of year. Clay is not a pure substance to make the pot it is mixed with the some additives to make the strong pot.

Pottery is not made up of raw clay, it is mixture of clay and other materials. Pottery is fried to a temperature high enough to mature the clay, meaning that; high temperature hardens the piece to hold water.

The hole in the pots is used to keep the pot water as cool. The ancient potters burnishing the surface with the hard substance before firing.